The currently available system module usually includes a housing and a circuit module provided in the housing. The circuit module consists of a main board, and a plurality of electronic elements mounted on the main board, such as a central processing unit (CPU), a hard disk, a memory, and integrated circuits (IC's).
Since the electronic elements produce heat during operation thereof, vents and cooling fans are normally provided on the system module at proper positions corresponding to the heat-producing electronic elements to prevent the electronic elements from overheated to result in failure or abnormal operation of the system module.
Following disadvantages are found in the conventional system module which uses the cooling fan to carry away heat produced by the electronic elements during operation thereof:    (1) The cooling fan requires high manufacturing cost.    (2) The cooling fan occupies a large space to adversely affect good utilization of an inner space of the system module.    (3) The cooling fan tends to produce noise during operation thereof.    (4) The cooling fan tends to become failed after having been used over a long time.